Recreating RAIDZ-1 pool to add a disk

[WindowsFreak]

Dear readers,

The current problem that I'm facing right now is adding a 4th disk to my raidz-1 pool. I have read some articles that it is not possible to expand your current raid pool. To give some context, I'm running 3x6TB Toshiba X300 drives in a RAIDZ-1 configuration (I know, 3 drive RAIDZ-1, not good). My pool currently has 1TB of free space out of 12TB. Adding a 4th disk isn't possible, so I want to destroy the current pool and recreate the new one with the 4th drive and use a better configuration.

/etc/pve/storage.cfg:

zfspool: zfspool
        pool vmdata
        content rootdir,images
        mountpoint /vmdata
        sparse 1

zpool status:

NAME        STATE     READ WRITE CKSUM
        vmdata      ONLINE         0         0            0
          raidz1-0   ONLINE         0         0            0
            sda         ONLINE         0         0            0
            sdb         ONLINE        0         0            0
            sdc         ONLINE         0         0            0

My current plan:
1) Back-up or run the running VM's to or from a NAS.
2) Move my virtualized TrueNAS Data to a NAS.
3) Destroy the pool.
4) Recreate the pool with the 4th disk and better configuration (different blocksize, different ashift value, compression, thinprovisioning).
5) Recreate the VM's from back-up or move the running vm's back to the new pool.
6) Move back my TrueNAS data.

I want to know what you guys think. Should I change my plan? What kind of configuration should I use?